title: LC-ESI-MS/MS method for the quantification of entecavir in human plasma and its application to bioequivalence study.
abstract: Liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) was used for a quantitative estimation of entecavir (EV) in human plasma using lamivudine (LM) as internal standard (IS). The method herein described is simple, sensitive, and specific. Chromatographic separation was performed on XBridge-C18, 4.6 mm × 50 mm, 5-μm column with an isocratic mobile phase composed of 10 mM ammonium hydrogen carbonate (pH 10.5):methanol (85:15 v/v), pumped at 0.3 ml/min. EV and LM were detected using proton adducts at m/z 278.1→152.1 and 230.2→112.0 in multiple reaction monitoring (MRM) positive mode. Solid phase extraction method was employed in the extraction of EV and LM from the biological matrix. This method was validated over a linear concentration range of 50.0-20000.0 pg/ml with a correlation coefficient (r) ≥0.9983. Intra and inter-day precision of EV was found within the range of 1.2-4.2 for EV and 4.4-4.5 for LM. EV was stable throughout three freeze/thaw cycles, bench top and postoperative studies. This method was successfully used in the analysis of plasma samples following oral administration of EV (0.5 mg) in 26 healthy human volunteers.
authors.affiliation: Siddharth Institute of Pharmacy, Nalanda Educational Society, Guntur, Andhrapradesh, India. baluchalla 99@yahoo.com
authors.forename: Balasekhara Reddy
authors.initials: BR
authors.lastname: Challa
authors.forename: Bahlul Z
authors.initials: BZ
authors.lastname: Awen
authors.forename: Babu Rao
authors.initials: BR
authors.lastname: Chandu
authors.forename: Shaik
authors.initials: S
authors.lastname: Rihanaparveen
mesh_terms: D000704:Analysis of Variance; D000998:Antiviral Agents / Q000097:blood / Q000493:pharmacokinetics; D019540:Area Under Curve; D002853:Chromatography, Liquid / Q000379:methods*; D004355:Drug Stability; D006147:Guanine / Q000031:analogs & derivatives* / Q000097:blood / Q000493:pharmacokinetics; D006801:Humans; D019259:Lamivudine / Q000032:analysis; D016014:Linear Models; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D052616:Solid Phase Extraction; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D053719:Tandem Mass Spectrometry / Q000379:methods*; D013810:Therapeutic Equivalency
chemical_list: D000998:Antiviral Agents; D019259:Lamivudine; C413685:entecavir; D006147:Guanine